The present invention relates to a method for using a software routine to determine modifications to metal stamping dies required to produce parts which meet design intent notwithstanding springback of the stamped material.
“Springback” is a phenomenon characterized by the regressive movement of stamped materials, particularly metals, following removal of a stamping from a press. In general, dies must be constructed to overbend materials, so as to produce finished parts meeting all required dimensional specifications. Springback compensation presents a major obstacle during stamping tool development, especially for lightweight materials such as aluminum and high strength steels. If not properly accommodated, springback may cause the shape of stamped panels or structures to deviate unacceptably from the intended design, rendering the stamped part unusable. As manufacturers of motor vehicles, in particular, move to the use of more aluminum, as well as higher strength steels, to save vehicle weight, the more pronounced springback tendencies affecting these materials adds as much as six months to the standard tooling development time of a vehicle manufacturer. This timing is incompatible with current market demands.
Known practices for compensating for springback primarily employ manual correction through an iterative, or trial-and-error, process. Thus, long years of experience are needed for an engineer to properly predict and correct for springback. This itself is a problem because materials such as aluminum and high strength steels have springback characteristics which are significantly different from those of mild steel—the staple material of vehicle bodies for more than one hundred years. The present invention provides a method for tooling design to accommodate shape distortions introduced by springback. Because the method may be completely computer based, it may be applied during early draw die development stages, without the necessity of a physical prototype.